Gaseous illuminant pyrotechnic systems

ABSTRACT

A HOMOGENEOUS PYROTECHNIC SYSTEM WHICH MAY BE USED FOR PRODUCING INTENSE ILLUMINATION SUCH AS THAT GENERATED BY FLARES. THE SYSTEM FUNCTIONS BY REACTING AN ALL-GASEOUS FUEL, OXIDIZER AND BORON ADDITIVE TO PRODUCE AN INTENSE FLAME.

Patented May 22, 1973 United States Patent Ofice 3,734,790 GASEOUSILLUMINANT PYROTECHNIC SYSTEMS Abraham D. Kirsheubaum, Succasunna, andFrancis R. Taylor, Mount Arlington, N.J., assiguors to the United Statesof America as represented by the Secretary of the Army No Drawing. Filedct.22, 1970, Ser. No. 83,210 Int. C1. (3061 15/00 U.S. Cl. 149-22 7Claims ABSTRACT OF THE DISCLOSURE A homogeneous pyrotechnic system whichmay be used for producing intense illumination such as that generated byflares. The system functions by reacting an all-gaseous guel, oxidizerand boron additive to produce an intense ame.

The invention described herein may be manufactured, used and licensed byor for the Government for governmental purposes without the payment tous of any royalty thereon.

. BACKGROUND OF THE INVENTION This invention relates to a homogeneouspyrotechnic system for use in making flares of variable intensity,burning rate and 'magnification.

Prior high altitude pyrotechnic systems were composed of mixtures offinely divided metal fuels and inorganic oxidants in a solid state.

The solid systems were made by blending the ingredients of desiredparticle size with approximately 5-10% of organic binder in anappropriate solvent. The resulting mixture was loaded in incrementsunder pressure into paper, plastic or metal tubes. These flares werethen cured and dried under controlled conditions.

In the past these systems exhibited variable burning performancecharacteristics due to particle size, homogeneity, loading pressure,voids and case material. Also, once initiated, the burning process couldnot be stopped.

Excess metalin the flare which was vaporized in the burning process'andsubsequently burned in air to produce additional light, remainedunburned at high altitudes due to a lack of'oxygen.

g The subject invention, the use of an all gaseous system for flares,which operates by contacting a gaseous fuel, oxidizer, and boronadditive, overcomes all the disadvantages of the prior art heretoforedescribed.

Reproducible homogeneous mixtures are readily obtained, the system canbe turned on and off at will, and illumination levels and burning timescan be varied by increasing and decreasing the gaseous flow rate andflow time of the various gases.

Further, these all-gaseous systems do not require atmospheric oxygen andcan be used at both high and low temperatures thus providing a highaltitude capability.

. Finally, all-gaseous systems produce flames relatively free ofparticulate matter and consequently radiation from these flares can bemagnified and directed by appropriate reflectors.

It is, therefore,.an object of this invention to provide a homogeneouspyrotechnic systemsuperior to prior flare systems.

Another object is; to provide a pyrotechnic system which exhibitsincreased luminosity when compared to prior fiare systems. 7

A further object is to provide a pyrotechnic system which can functionat high altitudes and low temperatures.

Yet another object is to provide a pyrotechnic system which producesradiation responsive to reflection and magnification.

Other objects and many of the attendant advantages of this inventionwill be readily appreciated as the same become better understood fromthe following detailed description.

I A system has now been discovered that consists of a gaseous fuel,gaseous oxidizer and gaseous boron additive. It was found that ifcertain gaseous boron compounds such as boron trifluoride (3B,) ordiborane (B H were passed into high temperature gaseous flames such ashydrogen-oxygen difloride or hydrogen-oxygenflorine, a very bright lightwas obtained.

Various studies were made using different gaseous systems as radiationsources. Tests ran using a gaseous fuel of H and an oxidizer of 0 show,upon the addition of BF that a maximum light output of only 3880candleseconds per gram was attained. It was later discovered that bygoing to higher temperature flames greater light outputs were obtained.As a result H OF and H -O -F flames with high flame temperatures werefound to be ideal systems.

Two types of burners were used in studying various gaseous systems.Concentric tube and perforated ring-tube burners were used to measurethe light output of H -OF BE; and H O F -BF flames. A perforatedring-tube burner was used to study the light output of H --OF -B Hflames since plugging due to thermal decomposition occurred when thediborane system was used in the concentric tube burner. I

A calibrated Weston photovoltaic cell, Model 856 Y Y V with viscorfilter, was used in the following light output experiments.

Example I.--H O'F -BF system TABLE I.LIGHT OUTPUT OF Hz-OFz-BFz FLAMESConditions Volume Candlepercent seconds] Hz/OFz BFs gram The use of apolished aluminum'parabolic mirrorwith the system producing 14,410candleseconds/gram directionally increased the output 12 fold to 170,000candleseconds/ gram.

Example 11 Varying amounts of 0 were added to a H F -BF flame havingdifferent H -F ratios. A summaryof these results is presented in TableH.

A H OF gaseous system was ignited in a perforated ring tube burner. Themixture in a ratio of 2 parts fuel to 1 part oxidizer exhibited a lightoutput of less than 20 candleseconds/ grams. When a 4.4 vol. percent ofboron trifluoride (BF was added, the light output increased to 22,500candleseconds. The use of a parabolic reflector system further increasedthe directional output to 240,000 candleseconds/ gram.

Example IV A H OF gaseous system was ignited in a perforated ring-tubeburner. The mixture in a ratio of 3 parts fuel to 2 parts oxidizerexhibited a light output of less than 20 candleseconds/gram. When a 4vol. percent of diborane (B H was added, the light output increased to43,200 candleseconds/gram.

Example V A gaseous system of methane (CH oxygen difloride (P and borontrifluoride (BF was studied and the results shown in Table III.

TABLE III.--LIGHT OUTPUT OF CH4OF:-BF3 FLAMES Volume Candlepercentseconds] OFz/CH4 BF gram Example VI 4 Gaseous systems of acetylene (CHz), oxygen (0 or oxygen difluoride (0P and boron trifluoride (BF werealso tested. The results for the various ratios are shown in Table IV.

TABLE IV.LIGHT OUTPUT OF CzHa FLAMES Oxid- Volume Candleizer/ percent,seconds/ System 0 11 BF; gram C H 0 BF 1.02: 2.8 3,850 a r T- a 1.50:12.9 6,650 2. 07:1 3. 7, 250 2.54:1 4.3 7, 840 3.18:1 3.9 7,150 4. 45:13. 1 5, 850 1. 00:1 0 4, 000

C H OF BF 1.00:1 1.5 4,500 a r 2- a 1.61:1 2.0 8,350 2. 03: 1 3. 2 5,800 1. 00:1 0 6, 000

It is evident from the mixtures and results set forth in Examples I, H,III, IV, V and VI that the introduction of gaseous boron additives to agaseous fuel-oxyfluoride system greatly increases the' light output ofthe system.

When boron additives are added in the amount of 4.2- 6.5 vol. percent togaseous H OF mixtures having various ratios of 1:1 to 3:1, an increasefrom 20 candleseconds/gram to between 7,000 and 22,500candleseconds/gram was obtained.

In a H O F system of varying ratios (Ill-1.84:1 Hg/Fz) and (0.260.99:1og/Fg) the addition of a boron additive in the range of 2.5-4.7 vol.percent increased the light output from 20 candleseconds/gram to between12,000 to 15,250 candleseconds/gram.

Further, with the addition of a reflector system to the light emittingsystem, the directed light output can again be increased, e.g. H -OF -BF(22,500 candleseconds/ gram) plus a reflector yielded 240,000candleseconds/ gram. The use of a reflector system is made possible bythe lack of smoke and particulate matter produced by the ignition andcombustion of the system.

In the gaseous systems which employ methane and acetylene as fuels, thelight output is again increased but not as substantially as the hydrogensystems. This is due in part to the buildup of unoxidized carbon on theburner tip.

This invention provides a novel flare system having a simple, allgaseous, efficient, fuel-oxidizer-additive system. No atmospheric oxygenis required; therefore, this invention operates as efliciently at highaltitudes as it does at sea level.

The system eliminates the variable performance characteristics of olderflare technology. It also provides a method for controlling the amountof radiation by simply adjusting the gaseous flow.

This system also provides a capability for stopping and restarting theradiation.

Finally, the system provides superior luminosity when the boron additiveis incorporated in the system.

It is evident that other selected gaseous compounds can be used in placeof the specific fuels, oxidizers and additives mentioned to achieve thesame effect when in-- corporated into the system of our invention.

We wish it to be understood that we do not desire to be limited to theexact details described for obvious modi fication will occur to a personskilled in the art.

We claim:

1. An all gaseous system for use in flares comprising: a gaseous fuelselected from the group consisting of hydrogen (H and an aliphatichydrocarbon, a gaseous oxidizer selected from the group consisting ofoxygen difluoride (0P and a mixture of oxygen and fluorine (O /F and agaseous boron additive selected from the group consisting of borontrifluoride (BF and diborane 2. The system of claim 1 wherein saidgaseous fuel is hydrogen (H 3- The system of claim 1 wherein saidgaseous boron additive is boron trifluoride (BF;,).

4. The system of claim 1 wherein said gaseous boron additive is diborane(B H 5. The system of claim 1 wherein the gaseous fuel is an aliphatichydrocarbon.

6. The system of claim 1 wherein the aliphatic hydrocarbon is selectedfrom the group consisting of methane (CH and acetylene (C H 7. Thesystem of claim 1 wherein the gaseous boron additive does not exceedabout 6.5% by volume.

References Cited UNITED STATES PATENTS 3,030,423 4/1962 Alley et al.149--22X 3,092,664 6/1963 Clark et al. 14922X 3,135,802 16/ 1964Kendrick III et al. 149-22 X 3,159,681 12/1964 Stange et al 14922X3,203,979 8/1965 Ager, Jr. et al. 149-22X 3,293,303 12/1966 Lawton et a1149-22 X CARL D. QUARFORTH, Primary Examiner P. A. NELSON, AssistantExaminer U.S. Cl. X.R.

